This image, by White-House photographer Cecil Stoughton, depicts the presidential motorcade as it passed through Dallas on November 23, 1963. The exact location of this scene is Main Street at Griffin Street. Public-domain image online via the JFK Presidential Library and Museum.
Leaving the crowds at Love Field, JFK got into his bubble-top Lincoln limousine. The weather was beautiful by this time, and Kennedy wanted to acknowledge the crowds that had gathered along the motorcade's route.
The top of the limo was off and its windows were down. The car, bearing license number "GG 300," was dubbed "X-100" by the Secret Service.
The President would travel to the Trade Mart where he was scheduled to give a speech. Everyone in and around Dallas knew the motorcade's route since it had been widely publicized. Crowds along the streets were estimated at eight to eleven people deep.
As the motorcade turned on to Elm Street, Abraham Zapruder, a local businessman, waited with his Bell and Howell 8mm camera. He had found a great place to stand (scroll down 60%) - on top of a concrete plinth. His secretary, standing behind him, would provide support since Zapruder sometimes suffered from vertigo. He waited for the President's car to reach his line of sight.
On the sixth floor of the School Book Depository building, the alleged assassin, Lee Oswald, also waited. A new employee of the depository warehouse, Oswald would soon have an excellent view of the President's car. (Follow this link to see a live webcam shot from "the sniper's perch.")
With him Oswald had a powerful Mannlicher-Carcano rifle (which he had purchased from a mail-order ad published in American Rifleman) plus several 6.5 mm cartridges. It is believed he carried the hidden rifle to work in a paper sack.
As soon as he could see the President's limo, which was traveling at about 11.2 miles per hour, Zapruder aimed his camera at the car and recorded the President's visit. Oswald, meanwhile, allegedly aimed his rifle at the same moving target.